The present invention relates to a new use for 5HT3-receptor-antagonists. CFS, chronic fatigue syndrome, was defined as a diagnostic entity at the end of the eighties and has been the subject of numerous studies and publications. Particularly problematic with respect to the diagnosis of CFS is the fact that a complex of symptoms of a pathological fatigue and susceptibility to fatigue is present, wherein the present symptoms are at least partially also to be encountered in a number of other internistic and psychiatric illnesses.
Thus, one must note the absence of symptoms, other than those which can be attributed to other illnesses, useful when diagnosing CFS.
Principally there is the question of what fatigue actually is. Generally, it is referred to as a physiological lack of capability, but may also be felt as lack of drive, lack of stamina in and physical weakness. Mental fatigue can be divided into a bad ability to concentrate and remember, lack of interest in activities and sleepiness throughout the day.
On the other hand fatigue is a natural phenomenon occurring after physical or psychological stress which goes away after resting or sleeping. Thus, the differentiation between xe2x80x9cnormalxe2x80x9d and xe2x80x9cabnormalxe2x80x9d fatigue is of importance. It is helpful to note that patients suffering from CFS usually also suffer from further symptoms which can be employed for diagnosis.
Since comparatively short term conditions of fatigue may occur during or after an illness or under strong and lasting stress, one concludes the presence of CFS as chronic illness only on the occasion of symptoms persisting for at least six months.
Generally, the presence of CFS is determined in a patient in whom the fatigue is medically not explainable even after careful clinical investigation. It is generally acknowledged that patients with a defined organic illness are to be excluded from the group of CFS patients. With respect to psychological illnesses, there is less agreement in relation to a corresponding exclusion. Some scientists are of the opinion that patients suffering from depression and anxiety should be excluded since an appropriate explanation for the fatigue in these patients is present. Other scientists are of a different opinion.
In the presence of CFS, symptoms of a chronic mental and physical fatigue usually occur which grow worse with activity and are often accompanied by pain in the muscles. In this respect, patients frequently report that they are fit and capable for a short period of time, but then suffer from heavy fatigue for hours or days. Further symptoms that ordinarily are reported include non-relaxing sleep, dizziness and breathlessness as well as head aches and further symptoms. Depressive periods and conditions of anxiety also occur in part of the patients. The diagnosis of CFS is therefore always a diagnosis by means of exclusion.
Until now no effective way of treatment could be found for treating CFS. Frequently antidepressants are employed for therapy, but a first comprehensive, randomized placebo-controlled investigation on antidepressants was negative in result (Vercoulen, Jan H. M. M. et al., Lancet 1996, 347:858-61). The subject of the referenced investigation was fluoxetin, wherein in the end not even patients with accompanying symptoms of depression showed a positive result in response to a daily dose of 20 mg fluoxetin. This already points out a specific pathogenesis of CFS in contrast to depressive illnesses.
Studies indicate there are concrete indications for serotonic activity in the brain, such as is shown by the significantly increased rise of prolactin in the serum after an acute application of D-Feufluoroamin on patients with CFS.
Studies have become known according to which there are concrete indications for a serotonic activity in the brain, as the significantly increased rise of prolactin in the serum after an acute application of D-Feufluoroamin on patients with CFS shows.
It is generally to be noticed that indications of a convenient and effective therapy for the treatment of CFS are lacking.
It is object of the present invention to provide compounds that are suitable for the manufactured of drugs for the treatment of CFS.
The present object is achieved by the features of claim 1. Advantageous embodiments of the invention form the subject matter of the depending claims.
The present invention is based on the finding that the use of antidepressants with CFS which amplify the action of serotonin is not appropriate, which is also evidenced by the cited study with respect to fluoxetin. First, this is a turn away from therapeutic methods that were customary until now and which essentially were focussed on the presence of depressive conditions. Thus, the use of substances is suggested which reduces the effect of serotonin and which are canalized by the subgroup of the so called 5HT3-receptors. According to tile invention, the pharmacologically known class of the highly specific 5HT3-receptor-antagonists, which for example find application in the treatment of the emesis in the chemotherapy of cancer, are suited for this purpose.
In an advantageous embodiment of the present invention Alosetron, Tropisetron, Ondansetron, Granisetron, Bemesetron or combinations of at least two of the foregoing, very selective acting substances are employed as 5HT3-receptor-antagonists. In this respect it is preferred that the amount of active substance in one dosage unit amounts to 2 to 10 mg, an amount of 5 to 8 mg active substance in one dosage unit being especially preferred. A daily dosage comprises generally an amount of active substance of 2 to 20 mg, particularly preferred is an amount of active substance of 5 to 16 mg. If necessary, those skilled in the art also know how to vary the active substance in a dosage unit or the level of the daily dosage according to the requirements. The factors determining this, such as body weight, overall constitution, response to the treatment and the like will constantly be monitored by the artisan in order to be able to react accordingly and adjust the amount of active substance in a dosage unit or to adjust the daily dosage if necessary.
Preferably, the substances that are used for producing the drug according to the invention, 5HT3, receptor-antagonists, are processed to an oral or intravenous form of administration to provide possibilities for variation in the application and for providing a possibly most gentle administration for the respective patient.